Transactions. 



m 



> 



The Awatere Area. 



A view up the Awatere Valley from a point near the railway bridge 

 shows a succession of broad and high terraces. It seems probable that an 



accurate survey of the terraces would show that 

 some of them can be correlated on both sides 

 of the river as remnants of dissected flood-plains 

 that mark stationary episodes in a movement of 

 uplift ; while, on the other hand, there can be no 

 doubt that a number of the terrace remnants have 

 no such significance, but have a merely local de- 

 velopment, and simply mark lateral swings of the 

 river-channel during down-cutting. 



It will here suffice to refer to the highest of 

 the valley-floor remnants noted and to some lower 

 series of terraces that indicate prolonged standstills. 

 The highest patch of superficial gravel noted by 

 the writer in the lower valley occurs on the top 

 of an isolated, rounded hill, 964 ft. high, situated 

 about two miles south-west of the Awatere rail- 

 way bridge. The top and flanks of the hill are 

 thickly covered by fluviatile gravel consisting of 

 pebbles of clastic and igneous locks similai to 

 those in the bed of the Awatere Eiver to-day. 

 The rock composing the hill being a weak mudstone, 

 the surface of which has been sculptured to mature 

 outlines during later erosion periods, its top does 

 not preserve a flat remnant of the ancient flood - 

 plain, the height of which above present sea-level 

 must, therefore, have been somewhat greater than 

 the present height of the hill. The height at this 

 point, above present sea-level, of the bed of the 

 ancient Awatere, which was no doubt the stream 



is 

 a 



Pi 



■< 



Q 



fa 

 ft 

 ft 



M 



u 



fa 

 K 



E- 



O 



W 

 aj 



ft" 

 pi 



w 



IS 



GO 



< 



o 



05-5 



T3 cS 

 eS 



3© 



fa 



M ft 

 < O 



fa **■ -±z 



fa pj s 



O t) o o 



fa "*-• cc 



ii. ^ ? c 



in be — 



E- CO -IS fcL 



03 



<! ta 



E-i 

 H ° 



« "S 



c 

 fa 



fa 



c 



3 O 



i o 



bl) g> that spread the gravel, may be taken to be about 

 •S'p, 1,000 ft. Opposite this point the river is now 



o 

 3 b 



be 



fc ~3 



M 

 o 

 o 



fa 



about 200 ft. above sea-level. In the present cycle 

 it is a submature, steep-grade stream, whereas in 

 the ancient cycle in which the high-level gravels 

 were laid down it may have been fully mature 

 and may have had a flatter grade ; but, on the 

 other hand, the mouth may have been farther sea- 

 ward. It is, therefore, difficult to estimate the 

 height above sea-level at which the gravel was 

 originally deposited, but it was probably not more 

 than 200 ft., and its presence where it is now 

 found may b? taken to indicate elevation of 

 800 ft. Farther up the valley of the Awatere 

 terrace remnants are much higher above present 

 sea-level, but their distance from the mouth of 

 the river renders them of little value in estimating the amount of 

 uplift. 



Flat-topped interfluves that appear to be remnants of a suiface of senile 

 relief developed over a considerable area during a later pause in the move- 

 ment of uplift are now prominent on the seaward portion of the Awatere 



o 



c 



-C 



tl. 





